Titanium base alloys



United States Patent TITANIUM BASE ALLOYS Robert I. Jalfee, Worthington, and Horace R. Ogden and Daniel J. Maykuth, Columbus, Ohio, assignors, by mesne assignments, to Rem-Cru Titanium, lnc., Midland, Pa., a corporation of Pennsylvania No Drawing. Application December 31, 1954, Serial No. 479,242

12 Claims. (Cl. 75--175.5)

This invention pertains to strong, ductile and thermally stable, titanium-base alloys containing as essential constituents, aluminum, together with one or more of the elements selected from the group consisting of vanadium, columbium and tantalum.

The aluminum content may range from about 0.5 to 8% and the metal of the group vanadium, columbium and tantalum may range from about 0.5 to 40% and preferably from about 0.5 to 15% in aggregate, the aluminum content being on the low side of its range when the metal of the vanadium, columbium, tantalum group is on the high side of its range, and vice versa.

The alloys of the invention containing about to vanadium undergo marked age hardening on solution treating at about 700 to 800 C. and thereafter aging at about 300 to 600 C. The preferred aging heat treatment for most analyses comprises a solution treatment at about 700 750 C. followed by aging at about 500 C.

This application is a continuation-in-part of our c0- pending application Serial No. 326,776, filed December 17, 1952, which is in turn a continuation-in-part of our application Serial No. 209,903, filed February 7, 1951, now abandoned, and which is in turn a continuationin-part of our application Serial No. 151,314, filed March 22, 1950, now abandoned, and is also a continuationin-part of our copencling applications Serial No. 356,096, filed May 19, 1953, and Serial No. 409,252, filed February 9, 1954, both now abandoned.

As is known, the metal titanium in the pure state, assumes at temperatures below about 885 C. or 1625 F., a close-packed hexagonal microstructure known as the alpha phase, while at this temperature and above, it assumes a body-centered cubic structure known as the beta phase.

Certain substitutional alloying additions to the titanium base metal, among which may be mentioned aluminum, indium, antimony, tin, bismuth, lead, thallium, cadmium, zinc and silver, as well as the interstitials, carbon, oxygen and nitrogen, tend to stabilize the alpha phase.

Other substitutional alloying elements, when added in progressively increasing quantities, stabilize the beta phase at progressively lower temperatures, until a mixed-phase, alpha-beta or a stable all-beta microstructure is obtained at normal or atmospheric temperatures, or the beta phase undergoes a eutectoid reaction, depending on the character and amount of the beta stabilizers added.

Speaking in broadest terms, the beta stabilizers are Mn, Mo, Cr, Fe, V, W, Cb, Ta, Ni, Co, Si, Be, Zr and Cu. Within this broad category, however, only certain of the elements mentioned are suitable for producing mixedphase, alpha-beta alloys or all-beta alloys. These are the elements which form with titanium, beta-isomorphous systems or which have beta-eutectoid systems such that the decomposition of the beta phase into eutectoid is so sluggish that the alloys behave like those in a betaisomorphous system. The beta stabilizing elements of this type are V, Mo, Cb, Ta, Mn, Cr and Fe. Within this group, however, only Mo, V, Cb and Ta are beta-isomorphous. They form the most thermally stable betacontaining alloys, as a result of this beta-isomorphism.

It will be observed, therefore, that in the alloys of the present invention, the aluminum functions as an alphapromoter or stabilizer while the metal of the group vanadium, columbium and tantalum functions as a betapromoter or stabilizer. And since all of the elements of this group, namely, vanadium, columbium and tantalum, form, as above noted, beta-isomorphous systems with titanium, they, together with molybdenum, are the most desirable beta-promoters to be employed for producing mixed-phase, alpha-beta or all-beta alloys of titanium.

The all-alpha, all-beta and mixed-phase, alpha-beta alloys of titanium have their respective advantages and disadvantages. Generally speaking, the alpha alloys provide good all-around performance, having good weldability, and being strong and resistant to oxidation, both hot and cold, but are somewhat inferior as to ductility. The allbeta alloys, on the other hand, have excellent bendability and ductility, are strong both hot and cold, but somewhat vulnerable to atmospheric contamination, particularly at elevated temperatures. The mixed-phase, alpha-beta alloys provide a compromise performance as between allalpha and all-beta alloys, being strong when cold and warm, but weak hot, while possessing good bendability and ductility with a moderate degree of resistance to atmospheric contamination.

The alloys of the present invention are all of the mixedphase, alpha-beta 0r all-beta types, depending on the total amount of beta-promoters present. Within the range of about 0.5 to 10% or 12% of beta-promoters, the alloys are in general found to be of the mixed-phase, alphabeta structure with the many advantages associated with such alloys, including fair tolerance for carbon, oxygen or nitrogen, which tolerance is not present in the all-beta alloys. With higher additions of beta-promoters, the alloys are of the unstable or stable all-beta type, although the zone between the two is not definitely demarked.

For the all-beta alloys of the invention, namely, those containing high total content of beta-promoters, the aggregate content of the interstitials, carbon, oxygen and nirogen, should be kept under about 0.2% maximum. For the mixed-phase, alpha-beta alloys, i. e., those containing under about 10 or 12% of beta-promoters, the carbon tolerance increases to a maximum of about 0.5%, and there may also be present up to about 0.2% of either or both oxygen and nitrogen, for extremely low additions of the beta-isomorphous group metals referred to.

As above stated, the alloys of the invention are all characterized in a high degree of thermal stability, and

in being easily stabilized thermally, i. e., put into a condition such that they will not become embrittled by prolonged exposure to high temperatures. They also have excellent welding characteristics, in that they may be welded without appreciably reducing the ductility in the welded portions as compared to the non-welded portions.

As shown below, additions of the eutectoid-forming, beta-promoting elements aforesaid, particularly those which decompose sluggishly, may be made to the basic titanium-aluminum beta-isomorphous containing alloys. of the invention without unduly impairing their excellent thermal stability characteristics. Thus, for example, up to about one-half of the aggregate content of the betaisomorphous elements present may be replaced by the sluggishly decomposing element chromium, or up to about one-quarter by the somewhat less sluggishly decomposing elements manganese or iron, or up to about The following Table I gives test results on the room temperature mechanical properties and stability characteristics of representative ternary titaniumbase alloys according to the invention. All of the alloys thus tested were prepared by forging at 1800 F., followed by rolling at 1500 F. to 0.08", then descaled, again rolled at 1400 F. to 0.04", held 15 minutes at 1400 F., furnace cooled therefrom to 1100 F., held one hour thereat, air cooled thence to room temperature and descaled before testing. Also in Table I, Com mercial Purity T i-Base refers to titanium metal of corn mercial purity as produced by the magnesium reduction of titanium tetrachloride in accordance with the process described in the Kroll Patent 2,205,854, while Iodide Base" refers to titanium metal of high purity as produced by the iodide process described in the patent to Van Arkel 1,671,213.

TABLE I isomorphous alloys also the thermal Tensile Prop Min. Bend Rad. '1

Composition, Perp s i. X 1,000

cent (Balance Percent Percent Titanium) Elonga- Reduction tion VHN As Rolled and As Aged 45 0.2% mtimate in 1" in Annealed Hrs. at 750 F. Offset Strength Area Yield (Commercial Purity Tl-Base) A] Ch 4 2. 5 88 97 20 51 309 2. 3 2. 8 2. 1 2. 9 4 5 94 104 19 53 317 2. 7 2. 8 2. 8 2. Q 4 10 124 138 13 47 339 3. 2 5. 5 3. 4 5. 3 l 0. 5 30 71 98 20 33 222 0 0. 3 Br B1 A1 Ta 4 5 B5 93 23 51 306 2. 4 2. 4 1.9 1. 9 4 10 B9 98 20 52 317 2. 4 2. 0 1. S 1. 9 4 15 95 102 1.9 327 3. 0 2. 6 2. 0 1. 9 0. 5 30 74 15 31 215 0.5 1.0 1. 5 1. 6

Al Ta (Iodide Base) 27 43 44) 61 105 0 5 1 65 79 19 41 300 0.7 5 2 5 67 80 18 45 276 0.0 a..- 5 5 69 B1 18 43 294 1. 1 7.5 2.5 93 98 17 38 320 6. 7 c.

l Rolled at 1,550 F., annealed hr.

at 1,550 F. and quenched.

The following Table 11 gives data corresponding to that of Table I for various quaternary titanium-base alloys according to the invention, containing in addition to aluminum and at least one element of the beta-isomorphous group, also another beta-promoter selected from the beta-isomorphous and eutectoid beta-promoter groups. The headings in Table II have the same significance as in Table I.

TABLE II Tensile Prop. Min. Bend Bad. '1 p. s. i. X 1,000

Percent Percent Com osltlon, Percent Elon- Reduc- As Rolled As Aged (B nee Titanium) gatlon tlon in VHN and 48 Hrs.

0.2% Ultimate in 1" Area Annealed at 750 F.

Oflset Strength Yield Ml-5V1.5Fe--- 141 160 10 36 356 2. 2 1. 7/3. 5 LAl-5V-2.5Mn 145 150 5 33 343 2. 8 2. 4 140 144 11 40 353 2. 9 3.

4Al-5V2.50r 138 146 9 28 338 2. 4 2. 8 4A1-5V-2.5W.- 151 154 6 30 357 2. 7 3. 6 4Al-5V-50b--- 150 152 33 335 5. 4 3. 4 4Al-5V-5Ta 144 145 6 33 351 2. B 3. 3 4Al-5V-2N L 132 144 5 14 341 6. 9 Br 4Al-5V20o 154 160 5 27 308 2. 3 2. 0 4Al5V-2.5Cu 133 139 1 15 346 3. 6 3. 0 4Al50b1.5Fe 135 143 11 41 330 2. 1 2. 3 4Al-fiCb-2.5Mn- 144 148 7 38 337 2. 5 3. 6 4A15Cb-2.5Mo 135 141 9 25 350 3. 5 2. 8 4A15Cb-2.50r 139 145 ll 37 353 2. 4 3. 7 4A1-5Cb-2.5W 110 132 9 39 349 2. 3/6. 5 2. 1/10. 4 4Al-5Cb-5Ta 121 127 15 44 325 2. 7 2. 6 4Al5Cb5V 150 152 5 33 335 5. 4 3. 4 4Al-5O b2N1 114 124 5 25 311 3. 7 3. 9 4Al-5Cb-2Co.- 139 147 6 33 353 3. 8 8. 7 4A1-50b-2.5Gu 124 131 9 41 349 3. 4 4. 0 4Al-51a-l .5Fe 1 16 128 0 34 311 2. 3 2. 8 4Al-5Ta-25Mn- 126 129 8 36 333 2. 6 2. 6 4Al-5Ta-2.5Mo.- 122 130 44 340 2. 9 3. 1 4A1-5Ta-2.50r- 123 129 7 29 349 7. 5/10. 0 11. 6 4Al5In.2.5W 113 123 17 48 332 3. 0 4. 0 1Al-1V-4Fe 135 159 53 2Al-2V-8Fe 182 193 6 3Al-3V-12Fe 2Al-3V-5 each of Cr, Mn, M 294 4Al-5Ta- 121 127 15 44 325 2. 7 2. 6 4Al5'1a5V 144 145 6 33 351 2. 8 3. 3 4A1-5Ta-2Nl. 109 122 7 32 308 3. 2 3. 0 4A1-5Ta-2Co 108 127 4 26 330 7. 1 8. 7 4A15Ta-2.5Cu 110 117 11 40 34B 4. l 2. 9 3.8Al-2.5V-5.70r0.3M0 121 120 47 4. 0 3. 2

Comparing the test results of Tables I and H, it will be observed that whereas the ductility and thermal stability of the quaternary alloys are comparable to those of the ternary alloys, the tensile strength of the quaternary alloys is much higher than for the ternary alloys. Thus, whereas the offset yield and ultimate strength for the ternary, commercial purity titanium-base, alloys fall within ranges of about 85,000-l25,000 and 95,000-135,000 p. s. i., respectively, the corresponding ranges for the quaternary alloys are about 1l0,000150,000 and 125,000-160,000 p. s. i., respectively. On the average, therefore, the tensile strength is increased on the order of to Thus, the presence in the alloy of a multiplicity of beta-promoters imparts a marked increase in strength with retention of adequate ductility and thermal stability as compared to the alloys containing but one beta-promoter.

It will be seen from the above data that the alloys in accordance with the invention have high tensile strengths as compared to the unalloyed titanium-base metal, being at least 10% in excess thereof in each instance, and that they combine this high strength with an extremely high degree of ductility, such as to permit of forming, both hot and cold, as by forging, rolling, etc. Also that the alloys have high thermal stability as evidenced by the aging tests showing that their ductilities are practically unchanged as compared to the as rolled and annealed condition.

As shown by the data in Tables I and II, the minimum bend ductilities for the various analyses range in general from about 1 to under 7, with corresponding elongations of about 5 to 25% for most analyses, showing that these alloys are quite ductile. Where the alloys are to be used in the form of sheets, however, the minimum bend ductilities may range as high as 20, and where the alloys are to be used in massive form, the percent tensile elongation may range as low as about 2%.

As above stated, the alloys of the invention containing about 5 to 15% vanadium are susceptible to appreciable age hardening on solution treating and subsequent aging in the temperature ranges aforesaid. This is shown by the test results in Table III below, made on specimens prepared and tested as follows:

Ingols weighing one-half pound each were prepared from titanium sponge of commercial purity and high purity vanadium and aluminum by are melting the admixed starting ingredients in appropriate proportions, in a water-cooled copper crucible and in an inert or argon atmosphere. The initial ingots thus produced were inverted and again are melted as aforesaid to assure the production of a homogeneous alloy. The ingots as thus produced were forged at 980 C., cleaned up and rolled at 760 C. into 0.01" sheet, then held at 780 C. one-half hour and furnace-cooled to 600 C. followed by air cooling to room temperature. Longitudinal bend test specimens were then sheared from these sheets and were given various solution anneals consisting of 8 hours at 650 C., 4 hours at 700 C., 2 hours at 750 C., and 1 hour at 800 C. followed by Water quenching. All solution heat treatments as well as subsequent aging treatments were carried out under argon atmosphere with the specimens sealed in Vycor or Pyrex capsules. A specimen of each alloy in each of the above solution treated conditions plus a corresponding specimen fabricated as above described was then aged for 0, l, 4 and 16 hours at 300 C., 400 C., 500 C. and 600 C. Surface Vickers hardness and minimum bend radius values were then determined for each of the specimens as thus heat treated with results as given in the following Table III.

1 Hr. at 800 0.

2 21823581 mmwemaammeaaa 52.13545785447 L-m omzlqfmiomnmlL I. I6 TF3 T677745 a s aataaa VV VV V o'ys 2 Hr. at 750 0.

7851793373745 ZLZQWA iLZZQWZZna 0787 4 03057 f asata aaaaa 4 Hr. at 700 0.

TABLE HI Pi-4Al-5V 2553396844877 EZZZZA ZZZZZLL 6512948365755 iLKiiliZZLLLZ Heat Treatment Before Aging (quenched from Temperature) 8 Hr. at 650 0.

1661613 8 381 wamaaaamamwaa 8451 n 9 6 iizazaamaaza 33333333 3333 Properties of age ha'rder'zirig Ti-Al -V al 9035355444335 A KZZZZLZZZQWZL 244 522442 L&4 2

As Fabricated VHN MBILT VHN MBR,T VHN MBR,T VHN MBR,T VHN MBR,T

Temp., C.

Time, hours It 55 The following Table V gives for the alloys of Table III as well as for various other Ti-AlV base alloys, the tensible properties, the Vickers hardness and the minimum bend ductility, for these alloys as solution treated and aged at the temperatures and for the times indicated. Included in this table are alloys wherein other beta stabilizers such as molybdenum and chromium are substituted for part of the vanadium at the five and ten 55 percent total beta-stabilizer levels. Also included at the five and ten percent beta stabilizer levels, are the properties of the corresponding TiV alloys without alum- MBR, inum. All test results in Table V were made on specm imens fabricated into sheet as above outlined for the data of Table III.

As Aged stances, the age an actual improvement in ble IV gives a few exelected from Table priate temperatures and h the alloy analysis.

the solution treated condiend ductility as aged is well f about 20T for these alloys 30 As Solution Treated VHN MBR, VHN

TABLE IV Aging Solution Treatment Compositlon (Balance ment,

for appropriate times, varying wit will further be noted that, in many in hardening is accompanied by bend ductility as compared to tion, and that in general the b below the useful upper limit 0 in sheet form. The following Ta amples illustrative of the above and s III.

lat-10V-.-

TABLE V ies of aged Ti-Al-V alloys Tensile proper! TABLE V-Conttnued Solution Heat Aging Heat Tenslle Properties,

Treatment Treatment p. s. l. X 1,000 Percent Percent Elonga- Reduc- MBR T tlon in rich in VHN Time, 'lemp.. Time, Iem 1., 0.2% 1" Area L Hours 0. Hours C. Oflset Ult. Str.

Yield 'll-4Al-5V-5Cr (118-523-67) 700 135 140 11 22 322 0. 4 700 V 400 144 148 12 20 325 0. 4 700 1 500 165 175 18 378 1. 5 700 16 500 161 168 7 18 382 1. B 750 130 138 9 20 297 2.0 750 400 188 100 3 16 456 11.0 750 5 400 11. 5 750 1 500 180 209' 5 14 470 4. 3 750 4 500 197 205% 7 9 386 3. 0 750 16 500 190 202 5 13 454 D. 9 750 64 500 191 105 2 3 416 11. 3

'Ii-4Al-fiV-5Mo (RS-523-63) 700 126 131 7 15 317 0. 5 700 1'5 400 133 138 8 24 323 0. 6 700 1 600 147 152 7 12 354 1.7 700 16 500 151 155 9 18 337 1. 5 750 116 139 7 16 305 0 750 l5 400 170 176 1 11 410 2.5 750 5 400 401 4 W121 750 l 500 166 183 3 13 436 1. 9 750 4 500 189 197 5 12 422 3. 6 750 16 500 175 178 5 15 403 2. 2/ 13. 5 750 64 500 161 166 5 17 392 2. 4

Ti-4Al-15V (RS-52344) It will be seen from the above data that whereas the Ti-SV binary alloy undergoes no appreciable hardening and strengthening as a result of the aging treatment, the addition of the aluminum introduces a marked hardening and strengthening action, accompanied by some loss of tensile elongation, but with practically no loss of bend ductility. Thus the optimum aging treatment increased the tensile strength of the Ti4Al-5V specimens about 20,000 to 30,000 p. s. i. while retaining adequate tensile elongation for fabrication purposes and holding the minimum bend ductility value below about 3T.

At the ten percent beta stabilizer level the Ti-lOV binary alloy has a relatively high tensile strength and zero tensile elongation as solution treated. Subsequent aging in general results in a considerable reduction in tensile strength accompanied by an increase in tensile elongation. The bend ductility is not materially influenced except for short time aging at about 400 C. which produces considerable embrittlement.

The addition of aluminum greatly reduces the strength and increases the ductility in the solution treated condition and also increases the spread between yield and ultimate strengths, thereby greatly facilitating the ease of fabrication and formability of the alloy in this condition. Thus the ternary Ti-4Al-l0V alloy as a solution treated has a yield strength of 66,0009l,000 p. s. i. and an ultimate strength of l32,000138,000 p. s. i. The tensile elongation is 10% and the bend ductility 1.3-2T. On aging the ultimate strength of this alloy may be increased up to about 190,000 p; s. i. with retention of a tensile elongation of at least 4% and a bend ductility not exceeding 2.0T, or up to about 215,000 p. s. i. with accompanying tensile elongation of 2.0% and bend ductility of 7.4T. As above stated, these alloys are useful in sheet form with bend ductilities as high as 201 and are useful as forgings with tensile elongations as low as 1 or 2%.

It will further be noted that the substitution of other beta stabilizers such as chromium or molybdenum for part of the vanadium, greatly increases the ductility of the as aged alloy without loss of strength.

As the beta stabilizer content is increased to the 15% level, the strengthening efiect or aging remains high although accompanied by considerable loss in ductility.

The data in the foregoing tables, therefore, establishes that the alloys of the invention containing about 545% vanadium or the equivalent thereof, undergo tremendous strengthening on appropriate solution treating and aging with retention in general of adequate dutility. The tensile strengths ranging up to 200,000 p. s. i. and above class these age-hardened alloys among the strongest metals available.

The alloys of the invention may be made by melt casting in a cold mold, employing an electric arc in an inert atmosphere, or may be produced in other ways in which the alloy is rendered molten before casting.

What is claimed is:

1. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to 15% vanadium, carbon up to 0.5%, and up to a total of 0.2% of oxygen and nitrogen, balance substantially titanium characterized in having in the annealed condition, a minimum bend ductility of not more than 20T, a minimum tensile elongation of about 10%, a tensile strength at least 30% in excess of the unalloyed titanium base metal and a beta-containing microstructure.

2. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to 15% columbium, carbon up to 0.5%, and up to a total of 0.2% of oxygen and nitrogen, balance substantially titanium characterized in having in the annealed condition, a minimum bend ductility of not more than 2-0T, a minimum tensile elongation of about 10%, a tensile strength at least 30% in excess of the unalloyed titanium base metal and a beta-containing microstructure.

3. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to 15% tantalum, carbon up to 0.5%, and up to a total of about 0.2% of oxygen and 13 nitrogen, balance substantially titanium characterized in having in the annealed condition, a minimum bend ductility of not more than 2eT, a minimum tensile elongation of about 10%, a tensile strength at least 30% in excess of the unalloyed titanium base metal and a beta-containing microstructure.

4. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum and 5 to 15% vanadium, balance substantially titanium, characterized in undergoing marked age hardening and strengthening on solution treati ing at about 700 to 800 C. and thereafter aging at about 300 to 500 C.

5. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to 15 of beta-promoting elements, at least one of which is vanadium, the content of beta-promoting elements other than vanadium not exceeding one-half the vanadium content, balance substantially titanium, said alloy being characterized in undergoing marked age hardening and strengthening on solution treating at about 700 to 800 C. and thereafter aging at about 300 to 500 C.

6. A titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum and 0.5 to 15% vanadium, balance substantially titanium, characterized in being age hardenable by solution treating at about 700 to 800 C. and Lt.

subsequent aging at about 300 to 500 C. to impart in ultimate strength of at least 140,000 p. s. i., a tensile elongation of at least 2% and a minimum bend ductility of not over 20T.

7. The method of age hardening a titanium-base alloy consisting essentially of about: 0.5 to 8% aluminum and 0.5 to 15% vanadium, which consists in soaking at a temperature of about 650 to 800 C. and thereafter aging at about 300 to 600 C.

8. An alloy consisting essentially of about: 0.5 to 8% 13.

annealed condition a minimum bend ductility of not more than 20T, a minimum tensile elongation of about 10%, and a tensile strength at least 30% in excess of the unalloyed titanium base metal.

9. An alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to of metal of the group vanadiiii) um, columbium and tantalum, balance substantially titanium, characterized in having in the annealed condition a minimum bend ductility of not more than T, a minimum tensile elongation of about 10% and a tensile strength at least in excess of the unalloyed titanium base metal.

it). An alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to under 10% of metal of the group vanadium, columbium and tantalum; chromium up to one-half the metal of said group present; metal of the group manganese and iron up to one-quarter of the metal of the group vanadium, columbium and tantalum present; metal of the group tungsten, copper, nickel, cobalt, silicon and beryllium up to one-eighth of the metal of the group vanadium, columbium and tantalum present; up to 0.5% carbon, up to a total of 0.2% of oxygen and nitrogen, balance substantially tiitanium, characterized in having a tensile strength at least 30% in excess of the unalloyed titanium base metal, a minimum bend ductility of under 20T and a tensile elongation of at least 5%.

11. An alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to under 10% of metal of the group vanadium, columbium and tantalum; up to 0.5% carbon, up to a total of 0.2% of oxygen and nitrogen, balance substantially titanium, characterized in having a tensile strength at least 30% in excess of the unalloyed titanium base metal, a minimum bend ductility of under 20T and a tensile elongation of at least 5%.

12. A titanium base alloy consisting essentially of about: 0.5 to 8% aluminum, 0.5 to 15% vanadium, 0.5 to 5% of at least one element selected from the group consisting of chromium and molybdenum, and the balance substantially titanium, characterized in having in the annealed condition a tensile strength of at least 100,- 000 p. s. i.

References Cited in the file of this patent UNITED STATES PATENTS 2,554,031 Jaifee et al May 22, 1951 FOREIGN PATENTS 718,822 Germany Mar. 24, 1942 OTHER REFERENCES Project Rand, Titanium and Titanium Base Alloys, USAF Project MX 791, April 2, 1948, pages -44.

Titanium, Report of Symposium, prior knowledge date Dec. 16, 1948, sponsored by the Oflice of Naval Research, Dept. of the Navy, Washington, D. C., pages -129. 

1. A TITANIUM-BASE ALLOY CONSISTING ESSENTIALLY OF ABOUT: 0.5 TO 8% ALUMINUM, 0.5 TO 15% VANADIUM, CARBON UP TO 0.5%, AND UP TO A TOTAL OF 0.2% OF OXYGEN AND NITROGEN, BALANCE SUBSTANTIALLY TITANIUM CHARACTERIZED IN HAVING IN THE ANNEALED CONDITION, A MINIMUM BEND DUCTILITY OF NOT MORE THAN 20T, A MINIMUM TENSILE ELONGATION OF ABOUT 10%, TO TENSILE STRENGTH AT LEAST 30% IN EXCESS OF THE UNALLOYED TITANIUM BASE METAL AND A BETA-CONTAINING MICROSTRUCTURE. 